The present invention relates to improvements in apparatus for introducing stacks of sheets into cartons or other types of containers. More particularly, the invention relates to improvements in apparatus for accumulating discrete sheets or layers of superimposed sheets into stacks of superimposed discrete sheets or layers prior to admission of the thus accumulated stacks into cartons or other types of containers.
It is already known to accumulate layers of paper sheets or the like into stacks of superimposed layers prior to introduction of the thus obtained stacks into cartons or like containers. For example, German Utility Model No. 82 06 480.6 discloses an apparatus having a feeding conveyor which delivers a succession of layers into the open upper end of a duct wherein the layers descend and land on top of a bottom wall which is normally closed. When the bottom wall intercepts a predetermined number of layers, i.e., when it accumulates a fully grown stack of paper sheets or the like, the bottom wall is caused to open and to thus drop the fully grown stack whereby the latter descends by gravity through the open top of and into the interior of a container (such as a cardboard carton) therebelow. The bottom wall of the duct includes two sheet metal panels which are movable apart so as to provide a passage for gravitational descent of the fully grown stack.
A drawback of the just described conventional apparatus is that successive layers, and especially the lowermost layers, of a growing stack in the duct must descend by gravity through a considerable distance before they strike the top surface of the closed bottom wall in the deepmost region of the duct or the topmost layer on the closed bottom wall. This can lead to misalignment of layers in the interior of the duct and in the interior of the container. Therefore, the German Utility Model proposes to provide the duct with a vibrator which shakes the duct during introduction and dwell of layers on top of the closed bottom wall and to thus enhance the likelihood of the formation of a stack wherein the layers are accurately aligned with and fully overlap each other. As a rule, the dimensions of the duct closely approximate the desired dimensions of the stack which is to be accumulated therein.
It has been found that mere shaking of the duct and/or the bottom wall, even in conjunction with the aforediscussed dimensioning of the duct, does not suffice to invariably ensure the formation of accurately formed stacks and predictable introduction of stacks into cartons or analogous containers. Furthermore, the provision of one or more vibrators entails continuous consumption of electrical or other energy and the vibrator or vibrators generate noise which is unpleasant to the workers and can affect their health and/or ability to concentrate.